So what costs more?

My wife is a little pissy because the electric bill came and it's 180. It used to be about 90. I'm sure the tank costs some but I swear it's because we ran the in-window AC 24/7. She swears it's the tank. What do you guys think. Any experts on electricity?

 

I don't like linking to other forums but RC has a great calculator here

 

I think it would depend on lighting schedule and how long/often the AC ran. That said, my vote is Biocube.

 

This little toy will tell you for sure. They sell for $27 bucks at my local Lowes.
Review: Kill-a-Watt Electricity Usage Monitor

 

window ac units kill electricity . i figured out my 90 gallon tank witch had 60 watts for the return 35 for the skimmer 12 watts for the power heads that was 24-7 240 for actinic 8 hours a day an aditional 230 for daylights 6 hours a day and when i figured it out it was arround 19 bucks a month

most window ac units go anywere from 600-1450 watts depending on btu easyest formula is units amp draw times the voltage to get the wattage but if the unit is undersized its busting its butt to keep the room or rooms cool it could be running 14-20 hours a day sometimes its better on the bill if the unit is oversized even though the amp draw is higher it has to work less to maintain tempiture if that makes any sence

but keep in mind just becose the ac is on dose not mean the compressor is running just may be the internal fan is running witch is about 50-80 watts depending on size as well

i just cant see that a 29 hqi takeing that mutch power 200 watt bulb 6-8 hours a day return pump at the most 30 watts skimmer 20 watts heater 100 watts possibly 2 hours a day most home pc's draw more in a 24 hour piriod than that IMO

 

Yeah that's what I thought. The calc says my tank costs about $12 and the AC costs about $70.

 

I don't know how long your tank has been set-up, but it only makes since that if you add something new to your electricity load that your electric bill would go up. Especially if you are running the A/C 24/7. Good luck with your wife, but I really don't think it is your tank.

 

That's close to my estimate, just judging by the bill-- Tank=$10-12, AC=$80+, depending on the actual temp outside.

 

How many BTUs is the AC. The light is 150W, really it isn't 150, it likely somewhere between 150 and 200, so, let's guesstimate 175.

How big is the AC?
you can get a rough idea of the AC by converting BTUs to watts. Here:
Watts to Btus (Th)/Hour Conversion Calculator

Lets say it's 10000BTU, that's about 2928W

So, if you have both on 12 hours, that's

175 * 12 = (2100/1000) = 2.1 kw/H per day for the light, at say $0.12 per kw/h is
$0.252 per day or 0.252 * 30 days = $7.56 per month.


The AC would be:
2928 * 12 = (35136 / 1000) = 35.135 kw/h per day, again at $0.12 per kw/h is
$4.216 per day or 4.216 * 30 days = $126 per month.

Granted, that's assuming the AC is running full throttle, which would probably only be the case if it's undersized for the room. Maybe it's only running 25% capacity, then it's still about $31.5 per month though. So, any way you look at it, the AC is going to cost way more.... As others have said a kill-a-watt is the best way to tell the exact numbers, but no question the AC costs more.


Edit: I see in your original post, you said you ran the AC 24/7. So, it could even be more...

 

let me tell you without a doubt it is your AC. I live in florida and we run the AC about 7 months a year or more and as soon as we shut it off for "the winter(i know funny)" my electric bill is cut in half.